سید Sayyid (also rendered as 'Sayed' or, in Malaysia and The Subcontinent, as Syed) is an honorific title often given to descendants of the Prophet Muhammad through his grandson, Hussain and Hassan (Descendants of Hassan were known as Sharif in the Arab world.).

The word means literally "lord" or "prince"—the closest English equivalent would be Sir. It is traditionally used to refer to those claiming descent from the Prophet Muhammad, through the sons of his daughter Fatima Zahra and son-in-law Ali ibn Abi Talib. Sayyids receive Islamic tax called Khums, a special tax levied under Islamic law. Sayyids are considered spiritually and socially supreme in the Islamic world.

In the early days of Islam, Sayyids were active in spreading Islam throughout the Arab, South Asian Countries and Indian subcontinent.

In the Arab world itself, with the exception of Iraq, the word is still used as a substitute for Mister, as in Sayyid John Smith.

The surnames of Sayyids from which Imam they descend.

1. Imam Ali - Alvi (from sons that are NOT from Fatima Zahra - daughter of the Prophet Muhammad)

• Below this line are known as Fatimi Sayyids *

2. Imam Hassan - Hassani, Tabatabai

3. Imam Hussain - reference below

4. Imam Zainul Abideen - Abidi (and Zaidi is specifically from his son Zaid)

5. Imam Mohammad al-Baqir - Baqri

6. Imam Jaafar as-Sadiq - Jafri, Jaffery

7. Imam Musa al-Kadhim - Musavi, Kazmi, Musawi, Moosavi

8. Imam Ali al-Ridha - Rizvi, Razavi

9. Imam Mohammad at-Taqi al-Jawad - Taqvi, Jawadi

10. Imam Ali an-Naqi - Naqvi, Naqavi

11. Imam Hassan al-Askari - None.

12. Imam Mohammad al-Mahdi - None.

There are also Hashimi Sayyids, those who are the descendents of Abu Talib, uncle of the Prophet Muhammad, from his sons Jafar, Aqeel and Talib.

Famous Sayyids

• Shia Imams
• Syed Ali as-Sistani
• Syed Moqtada as-Sadr
• Syed Abul Alaa Maududi
• Syed Qutb
• Ayatollah Ruhollah Khomeini
• Syed Dildar Ali a.k.a Ghufran Ma'ab
• Syed Kalbe Hussain
• Syed Ali Khamenei
• Syed Ali Naqi Naqvi
• Syed Aqeel al-Gharavi